How the wrong genes are repressed

Jun 11, 2010
PRC2 is brought to its target genes though binding to short RNA transcribed by RNA polymerase II. It blocks full transcription of developmental regulator genes that would otherwise act to alter the identity of the cell.

The mechanism by which 'polycomb' proteins critical for embyronic stem cell function and fate are targeted to DNA has been identified by UCL scientists.

The discovery, which has implications for the fields of stem cell and , is detailed in research published today in the journal Molecular Cell.

A key feature of is the suppression of that when later switched on lead to the differentiation of the cells into specific mature cell types, such as neurons or immune cells. Polycomb proteins, first discovered in , are known to play a critical role in the suppression of these developmental genes. PRC2 (polycomb repressive complex-2) is present in all multicellular organisms and has been shown to be important in stem cell differentiation and early embryonic development.

The study authors found that PRC2 is brought to its target genes though binding to a new class of short RNAs transcribed by RNA polymerase II. PRC2 can then methylate chromatin, preventing the activation of developmental regulator genes that would otherwise act to alter the identity of the cell.

Senior author Dr Richard Jenner, UCL Infection & Immunity, said: "We knew that different sets of genes are turned on in different cells and that polycomb proteins prevent the wrong genes from being turned on, for example polycomb prevents the activation of neuronal genes in immune cells. However, although polycomb proteins repress genes, they are actually in a poised state - some sort of gene activity seemed to be occurring.

"We wanted to find out what this activity was and our identification of these short RNAs explains this unusual gene state. Discovering that polycomb also binds to these RNAs shows how polycomb might be recruited to genes, which are then repressed to maintain the identities of different cell types. This has been a key question in the field for some time and has important implications for how we might be able to control cell fate in tissue engineering".

Explore further: Micro fingers for arranging single cells

More information: 'Short RNAs Are Transcribed from Repressed Polycomb Target Genes and Interact with Polycomb Repressive Complex-2' is published today in Molecular Cell.

Related Stories

Cancer is a stem cell issue

Feb 19, 2007

There is an urgent reason to study stem cells: stem cells are at the heart of some, if not all, cancers. Mounting evidence implicates a clutch of rogue stem cells brandishing ‘epigenetic’ marks as the main culprits in ...

Sugarcoating fruit fly development

May 29, 2009

Proteins are the executive agents that carry out all processes in a cell. Their activity is controlled and modified with the help of small chemical tags that can be dynamically added to and removed from the protein. 25 years ...

Recommended for you

Micro fingers for arranging single cells

Apr 24, 2015

Functional analysis of a cell, which is the fundamental unit of life, is important for gaining new insights into medical and pharmaceutical fields. For efficiently studying cell functions, it is essential ...

Detailed structure of human ribosome revealed

Apr 24, 2015

A team at the Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC - CNRS/Université de Strasbourg/Inserm) has evidenced, at the atomic scale, the three-dimensional structure of the complete ...

How to kill a protein

Apr 24, 2015

For decades scientists have been looking closely at how our cells make proteins. But the inverse is equally important: how cells kill them.

How RNA machinery navigates our genomic obstacle course

Apr 24, 2015

Once upon a time, scientists thought RNA polymerase—the molecule that kicks off protein synthesis by transcribing DNA into RNA—worked like a wind-up toy: Set it down at a start site in our DNA and it ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.